These are things you learn as you modernize an old boat. I put all new gauges in my '79 Formula Liberator ...including fuel. I noticed that the fuel gauge wouldn't work. Some investigation revealed that the original sending unit's ohm impedance doesn't match the new gauge...so I get to install a new sending unit!!

Live and learn.

I'm right there with ya. In all my new gauges, I got new oil pressure and water temp sending units. My fuel however works but is wrong. When empty the gauge is 3/4 and as I fill it it just goes to pegged full. Gotta figure it out. Lol

The one I need is $70 at Boat Owners Warehouse. I'm going to get one this week...I can't stant not knowing how much fuel I have...sort of like SCUBA with no air gauge !!!

I'm just fortunate I know where empty is. Don't ask me how I found out. But I know for sure now!! Lol

I'm in the same "boat". Need to switch out new sending unit for another new sending unit.....

Same boat here(not literally same boat) last owner put auto meter pro comp marine gauges in but no new sending units. Temps were off, oil pressure reads backwards, hooked up a manually to determine that, scary times there and fuel always reads full, that's bad. So instead of buying new sending units, I found original gauges. Haven't installed them but will prob do the important ones first like fuel oil and water.

Good luck.